Inverted F antennas are traditionally used in the field of communication. An inverted F antenna (IFA) typically includes a rectangular planar element located above a ground plane, a short circuiting plate or pin, and a feeding mechanism for the rectangular planar element. IFA is a variant of monopole antenna where the top section is folded down to be parallel with the ground plane. The folding is to reduce the height of the antenna, while maintaining a resonant trace length. The parallel section essentially introduces a capacitive load to the input impedance of the antenna, which is compensated by implementing a short-circuit stub. One end of the stub is normally connected to the ground plane.
Electromagnetic energy (e.g., microwave energy) has been used in various applications to supply energy to objects. For example, a microwave oven heats food using microwave energy. Microwave energy is usually transferred into a microwave cavity via waveguides. When electromagnetic energy is to be transferred by an energy radiating device (e.g., an antenna) into a cavity to process an object placed in the cavity, it may be desirable to maintain good coupling between the energy radiating device and the cavity containing the object in order to achieve high efficiency.